Endocrine Abstracts

Introduction: The aldosterone-to-renin ratio (A/R) is the most frequently used screening test for primary hyperaldosteronism (PH) and a confirmation test is recommended when it is high. We aimed to determine the frequency of PH in patients with high A/R and investigated possible clinical features that might help to prevent unnecesary confirmation tests.

Method: Patients who underwent saline infusion test because of high A/R (>3.8) were retrospectively reviewed. PH was diagnosed in patients with plasma aldosteron >10 ng/dl after 4 hours of saline infusion. Patients with postinfusion aldosteron level between 5–10 ng/dl and with <5 ng/dl were defined as indeterminate and not to have PH, respectively. Patients with and without PH were compared.

Results: There were 38 patients (27 female and 11 male) with a mean age of 55.18±10.13. Mean serum potassium (K) was 4.01±0.69 mmol/l and aldosteron was 30.24±14.61 ng/dl. Median renin and A/R were 2.015 ng/l and 12.913, respectively. After saline infusion test, the diagnosis of PH was confirmed in 17 (43.6%) and excluded in 11 (28.2%) patients. Indeterminate results were obtained in 10 (25.6%) patients. There were 9 female and 8 male patients with PH, while all 11 patients without PH were female (P=0.007). 16 (94.1%) patients with PH and 7 (63.6%) without PH were hypertensive (P=0.040). The age, presentation, adrenal imaging findings, sodium and renin were similar in patients with and without PH. Mean serum K were 3.57±0.65 mmol/l and 4.31±051 mmol/l in patients with and without PH, respectively (P=0.003). Mean aldosteron and median A/R were higher in patients with PH, however the differences were not statistically significant [For aldosteron; 36.67±15.38 ng/dl vs 25.14±13.02 ng/dl, P=0.050, for A/R 16.27 (4.90–264.50) and 7.36 (3.97–53.84), P=0.051]. Median aldosteron after saline infusion was 19.40 ng/dl (10.26–64.35) in patients with PH and 3.70 ng/dl (1.50–4.83) in patients without PH (P<0.001).

Conclusion: Confirmation of PH in less than half of patients with high A/R is suggestive for high false positivity of this screening method. It may be rational to repeat measurements before confirmation tests in women, patients without HT and without hypokalemia. However, male sex, presence of HT and hypokalemia seem to be stronger clinical findings that requires confirmation tests in patients with high A/R.